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THMG182 – Nitric Acid & Acetone Hotwash


We outline and analyze a listeners submitted incident that had some unique outcomes.

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At 1108 on February 12, 2019 local 9-1-1 received a report of a chemical explosion in a lab within the Research and Development division of the XXXXX, Inc.  The caller indicated that there had been an explosion in a lab and that there were no injuries.

Dispatch indicated that the two chemicals involved were nitric acid and acetone. The first due engine immediately requested our primary HazMat company who subsequently made the immediate request for our secondary team. Total response included two engine companies, one battalion chief, one safety officer, the division chief, HazMat 1 (Captain, Engineer, 2 firefighters), and HazMat 2 (Captain, 2 firefighters). There was a total of 6 HazMat Technicians on scene.

The first arriving engine company assumed command and began a size up of the building and situation. Representatives from the company indicated that a mixture of nitric acid and acetone had been inadvertently created and the employee handling the container placed the mixture in the corner of a lab.  The employee noticed the evidence of an exothermic reaction and was apparently looking for a secure disposal area for the mixture but the lab he walked in to did not have one. The initial incident commander procured SDS sheets for both chemicals and had company personnel sketch a map to the incident area.

The lab was approximately 1,000-1,200 square feet with one wall lined with cubicles for the employees and a large work area with all of the expected materials for a chemical research lab, except a safe place to discard potentially hazardous waste.  The container was a four gallon carboy and had been placed on a rolling cart in the far corner of the lab area. There was a cubicle partition on one side of the cart and exterior walls on two sides. We had access to the lab via the main entrance to the building with a long walk through hallways that lead to the incident area.  

The hot zone was determined to be the lab area that had controlled access through two doors. The corner of the lab that was directly involved in the explosion was visible through one door down a short hallway. The second door was used for HazMat team entry because it was a short hallway with a left turn to enter the lab and another left to get to the corner where the explosion occurred. The longer entry also allowed HazMat techs to use the emergency decon shower in the main hallway before going through decon outside of the facility.

HazMat captains assumed the roles of Operations and HazMat Safety.  HazMat officers elected to use Level B suits for entry. The initial entry team consisted of two personnel with acid absorbent pads, Drager Tubes for Nitric Acid and Acetone, Ph paper, and a five gas meter set up for O2, CO, LEL, VOC, and H2S.  The initial action plans consisted of the two man team entering through the main hallway and assess the situation for presence and/or concentration of vapors, amount of area involved, initial Ph reading of the wet spill area, and, if possible, stop any remaining reactions from taking place.

The initial report was that the carboy had exploded and sprayed the area from floor to ceiling in the nitric acid/acetone mixture. The mixture was fluid with some drying taking place in the nearest cubicle and on vertical surfaces where the concentration of the liquid was minimal.  Initial Ph reading confirmed the presence of a strong acid; air monitoring indicated a very slight VOC reading and 1 ppm reading of nitric acid. Entry Team 1 covered the spill area on the floor with acid absorbent pads and applied a thin layer of neutralization powder that was provided by the facility.

Entry Team 1 exited the lab through the main hallway and used the emergency shower in the hallway for a quick decon before exiting the building for simple water decon performed by an engine company staffed with HazMat operations level firefighters. Entry Team 2 made entry in Level B suits to prevent contamination of turnout gear to monitor conditions after initial mitigation measures. Entry Team 2 applied more neutralizing agent to areas not previously treated and tested the material’s resulting Ph.

Once the material was brought back to a neutral state Entry Team 2 exited the facility following the same decon procedure and path as Entry Team 1.  Entry Team 1 made one additional sweep of the lab for air monitoring before the outside contractor began cleanup of the affected area.

The Hazmat Guys

Author: The Hazmat Guys


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